The findings show that drought is strongly correlated with conflict due to limited resources. In an odd and depressing twist, though, the research indicates drought is becoming more common in parts of the world, and that could lead to drop in conflict because going to war over dry land might simply not be worth it.
The study published on Monday in the Proceedings of the National Academy of Sciences specifically examines scientists' belief that one of the major links between climate change and violent conflict is the cost versus the benefit to agricultural profits, which was formalized in an oft-cited 2009 paper. The findings in that paper show that during particularly dry years, it's more worth it for nations to recruit agricultural workers to stop farming and go to war to obtain more farming territory, because even though they'll miss out on the profits from that year's agriculture, they can make up the lost profits with their increased landholdings in the longer term. But if drought becomes normal, it doesn't make much sense to obtain new landholdings because they might not be very productive anyway.
"There is a robust empirical literature that shows that conflict is indeed more prevalent during abnormally dry years," Michele Muller-Itten, one of the study's authors, told Earther. "However... the dry years are no longer "˜abnormal,' and that changes the incentive structure."
Indeed, the new findings show that intra-regional war is more common when conditions are drier than average. But what's considered average is changing with many regions trending toward less rain overall. Conditions will continue shifting, and Muller-Itten said that as drought becomes more common, there may not be as much to gain from going to war to obtain more resources.
"After all, the reason why attacking a neighbour's land is attractive is because victory secures more landholdings for the future," she said. "If the dry year is the anomaly, these extra landholdings are attractive. But if all future years are bleak, the incentive for conflict disappears again."
In other words, there's no point in attacking your neighbouring nations for arable land if your neighbours' land isn't arable in the first place, and if conditions show no signs of getting better. The context of drought also matters, though. In some places, average rainfall may stay the same even as droughts get worse (like California, for example), something which Muller-Itten said could make conflict more likely. But in some places where drought becomes permanent or semi-permanent, conflict may drop. That's why she said researchers need to look not just at rainfall's changing average but also peaks and valleys.
The study doesn't account for all impacts of drought on conflict, and Muller-Itten stressed that the study doesn't show that we'll see less war in a heating world. Other variables, such as forced migration due to a lack of water for example, could increase the likelihood of war in some places. In 2015, for instance, Syria saw its worst drought in 900 years"one research shows was made more likely by climate change"as it was in the throes of a civil war. The devastating conditions forced thousands to emigrate within the nation, which aggravated instability in the region.
"For many combinations of parameters it still increases conflict," she said. "But the goal was more to show that you cannot make a simple extrapolation."